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    Is Cannabis Use Associated with Sedentary Behavior during Leisure Time? A Study in Canada, 2011–2012

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    Background: Sedentary behavior, defined as lying or sitting, is a global health concern. As researchers continue to identify modern-day risk factors for sedentary behavior, few have explored the role of illicit drug use. Objective: To examine the association between leisure-time sedentary behavior and cannabis use, in adolescents and adults. Methods: We conducted a cross-sectional study relating cannabis use to total leisure-time sedentary behavior (hr/wk using the computer, playing video games, watching television or videos, and reading for leisure) using data from the 2011–2012 Canadian Community Health Survey (CCHS), a population-based survey of Canadians age ≥12 years. Analyses were possible for 48,240 respondents in Saskatchewan, Ontario, and Nunavut who reported on sedentary behavior. We used logistic regression modeling to relate frequency of cannabis use (never, occasional, heavy) to high-risk sedentary behavior (<35 versus ≥35 hr/wk) overall and stratified by sex, age, and rural location. Results: Approximately 80% of respondents were ≥25 years old. In the fully-adjusted model, the odds of ≥35 hr/wk of sedentary behavior were 80% higher for heavy cannabis users versus never users (OR = 1.8, 95% CI: 1.4–2.3); in occasional cannabis users, the odds were 30% higher (OR = 1.3, 95% CI: 1.1–1.5). In stratified analyses, odds ratios were statistically significant among adults age 25–44 years and people living in nonrural settings. Conclusions/Importance: Our findings support dual lifestyle interventions targeting heavy cannabis use and excessive sedentary behavior simultaneously. Moreover, leisure-time sedentary behavior should be considered as a covariate in future epidemiologic models relating cannabis to health

    Evaluating the efficacy of predator removal in a conflict-prone world

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    Predators shape ecosystem structure and function through their direct and indirect effects on prey, which permeate through ecological communities. Predators are often perceived as competitors or threats to human values or well-being. This conflict has persisted for centuries, often resulting in predator removal (i.e. killing) via targeted culling, trapping, poisoning, and/or public hunts. Predator removal persists as a management strategy but requires scientific evaluation to assess the impacts of these actions, and to develop a way forward in a world where human-predator conflict may intensify due to predator reintroduction and rewilding, alongside an expanding human population. We reviewed literature investigating predator removal and focused on identifying instances of successes and failures. We found that predator removal was generally intended to protect domestic animals from depredation, to preserve prey species, or to mitigate risks of direct human conflict, corresponding to being conducted in farmland, wild land, or urban areas. Because of the different motivations for predator removal, there was no consistent definition of what success entailed so we developed one with which to assess studies we reviewed. Research tended to be retrospective and correlative and there were few controlled experimental approaches that evaluated whether predator removal met our definition of success, making formal meta-analysis impossible. Predator removal appeared to only be effective for the short-term, failing in the absence of sustained predator suppression. This means predator removal was typically an ineffective and costly approach to conflicts between human

    Modelling Transient Ground Surface Temperatures of Past Rockfall Events: Towards a Better Understanding of Failure Mechanisms in Changing Periglacial Environments

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    Despite the rising interest in mountain permafrost due to climatic changes and a noticed increase of registered rockfall events in the European Alps and other mountain ranges, little is known about transient thermal conditions in the detachment areas of rockfalls. Temperature conditions prior to the rockfall events of 144 past events in the European Alps were modelled with a physically based ground temperature model. To minimise the impact that uncertainty has on interpretations, only relative values were used, that is, percentiles obtained from cumulative distribution functions of the modelled ground surface temperatures from the beginning of the meteorological measurement series up to the event dates. Our results suggest that small and mid-sized rockfalls (volumes up to 100 000 m3) from high elevation occurred mainly during short-term periods of unusually high temperatures. This was neither found to be a result of the seasonal distribution (most analysed events in higher elevations occurred from July to September) nor of the longer-term temporal distribution (most analysed events occurred after 2000) only. Plausible explanations are either a destabilisation related to advective thaw or failure due to stress redistribution caused by large temperature variations. Large deep-seated rock slope failures (≥100 000 m3) in high elevation occurred all year round

    State Prices of Conditional Quantiles: New Evidence on Time Variation in the Pricing Kernel

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    Summary: We develop a set of statistics to represent the option-implied stochastic discount factor and we apply them to S&P 500 returns between 1990 and 2012. Our statistics, which we call state prices of conditional quantiles (SPOCQ), estimate the market's willingness to pay for insurance against outcomes in various quantiles of the return distribution. By estimating state prices at conditional quantiles, we separate variation in the shape of the pricing kernel from variation in the probability of a particular event. Thus, without imposing strong assumptions about the distribution of returns, we obtain a novel view of pricing-kernel dynamics. We document six features of SPOCQ for the S&P 500. Most notably, and in contrast to recent studies, we find that the price of downside risk decreases when volatility increases. Under a standard asset pricing model, this result implies that most changes in volatility stem from fluctuations in idiosyncratic risk. Consistent with this interpretation, no known systematic risk factors such as consumer sentiment, liquidity or macroeconomic risk can account for the negative relationship between the price of downside risk and volatility

    Hybrid controller for improved position control of quadrotors in Urban wind conditions

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    A hybrid control technique combining both proportional derivative (PD) and adaptive integral backstepping (AIB) control strategies is proposed for position control within a building-generated wind wake. Position hold performance for a quadrotor (˜2 kg, 0.5 × 0.5 m) within windfields obtained from large-eddy simulations are used to compare control strategies. Simulated results show that both the PD and AIB control approaches can outperform each other depending on position within the wake. Over multiple positions within a wake, simulations show the hybrid approach reduces the average volume within which the vehicle remains by approximately 50% over both an exclusively PD or AIB control approach. Simulations also show the hybrid approach can hold the quadrotor to within an average of approximately one body length of the desired position compared to one to two body lengths using a PD control and two body lengths using an AIB control. Flight tests performed using PD and hybrid approaches confirm the improved position hold ability of the hybrid controller in building wake environments. Flight data show the hybrid controller reduces the average volume within which the vehicle remains bounded by approximately 50% compared to the volume obtained using the PD controller

    Phenomenology of youth cultures and globalization: Lifeworlds and surplus meaning in changing times

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    This edited collection brings together scholars who draw on phenomenological approaches to understand the experiences of young people growing up under contemporary conditions of globalization. Phenomenology is both a philosophical and pragmatic approach to social sciences research, that takes as central the meaning-making experiences of research participants. One of the central contentions of this book is that phenomenology has long informed critical empirical approaches to youth cultures, yet until recently its role has not been thusly named. This volume aims to resuscitate and recuperate phenomenology as a robust empirical, theoretical, and methodological approach to youth cultures. Chapters explore the lifeworlds of young people from countries around the world, revealing the tensions, risks and opportunities that organize youth experiences

    Reconciling contradictory relationships between mobility and extinction risk in human-altered landscapes

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    Some empirical and theoretical studies suggest that more mobile species are less at risk in human-altered landscapes, while others suggest the opposite. We propose three novel hypotheses to explain these contradictory findings: (i) extinction risk increases with increasing mobility when mobility is measured as emigration, but decreases with increasing mobility when mobility is measured as immigration; (ii) the most mobile species (whether measured by emigration or immigration) in unaltered landscapes are least mobile in human-altered landscapes, so the relationship between mobility and risk is opposite when mobility is measured in unaltered and altered landscapes; and (iii) the mobility-risk relationship is ∩-shaped; thus, the relationship is apparently positive when studied species have low-to-intermediate mobility, but negative when species have intermediate-to-high mobility. We also evaluate a fourth hypothesis that had been previously theorized: that some landscape structures drive evolution of dispersal characteristics that increase both mobility and risk, while others drive evolut
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